1. Field of the Invention
The present invention pertains to a sulfide solid electrolyte material exhibiting high Li ion conductivity, a lithium solid battery and a method of preparing the sulfide solid electrolyte material.
2. Description of Related Art
With recent rapid prevalence of information related devices and communication devices such as PC, video camera and mobile phone, it is getting important to develop batteries utilized as their energy sources. Besides, in vehicle industry and the like, development of batteries for electric vehicles and hybrid vehicles has proceeded to achieve high output and high capacity. Among various batteries, lithium battery has currently been attracting in terms of its high energy density.
Lithium battery currently commercially available to us includes an electrolyte liquid containing a flammable organic solvent, and needs to be modified in terms of safety device attachment for preventing the rise in temperature resulting from short circuit, and in terms of structure and material for preventing short circuit. Meanwhile, lithium battery entirely composed of solid batteries with a solid electrolyte layer modified from the electrolyte liquid does not necessitate the flammable organic solvent, making it possible to simplify a safety device and achieve superior fabrication cost and productivity. Sulfide solid electrolyte material has been known as a solid electrolyte material used for such a solid electrolyte layer.
Sulfide solid electrolyte material exhibits high. Li ion conductivity and can be utilized for achieving high output of battery, and has been studied from various aspects so far. For example, Japanese Patent Application Publication No. 2008-004459 (JP 2008-004459 A) discloses that dehydrated toluene is added into the mixture of Li2S and P2S5 prior to performing wet mechanical milling.
For example, internal resistance of battery needs to be lowered for improving input and output of the battery. In particular, in a whole solid battery, it is important to reduce a resistance (direct current resistance and diffusion resistance) between solid electrolyte materials. These resistances are highly susceptible to Li ion conductivity of solid electrolyte material. In view of the above backgrounds, sulfide solid electrolyte material exhibiting high Li ion conductivity is required.